PROJECT ABSTRACT Postnatal health care is associated with reduced maternal and neonatal mortality, and results in improved rates of exclusive breastfeeding, immunization, and postnatal contraceptive use. Evidence from group care models such as Centering Pregnancy suggest social support may play an important role during perinatal care, but has not yet been extended to the postnatal period. Common logistical challenges of transportation and scheduling are exacerbated in India, our project site, by rural geographic distances, cultural and linguistic barriers to care, women's practice of postnatal seclusion and generally low levels of mobility in marriage; all combine to significantly reduce care postnatal care access. The current proposal seeks to develop a mobile interactive education and support group intervention, Maa Shishu Swasthya Sahayak Samooh (MeSSSSage), to improve the health and well-being of Indian women and infants in the postnatal period using a provider-moderated group approach. MeSSSSage will provide culturally and age tailored educational programming, increase women's health-related discussion with providers, refer women in a timely and appropriate manner, and connect them with a virtual social support group of other new mothers. The two-phase development of the intervention will include exploratory development on functions and platforms and a mixed-methods randomized pilot study using a factorial design of the specific intervention functions and platforms confirmed. The aims of this project are as follows: Aim 1. To develop optimal intervention functions, processes, and mHealth platforms for education and peer support among postnatal women in rural India; Aim 2. To assess the feasibility and acceptability of the optimized intervention; and Aim 3. To explore the preliminary effectiveness of the optimized intervention components on six-month maternal and neonatal health outcomes. This formative study uses a systematic, user- centered and experience-driven design approach to developing an mHealth educational and social support intervention, and the results will inform the most acceptable, feasible, and potentially efficacious intervention design to be robustly tested through an R01 mechanism to assess effectiveness for maternal and infant health outcomes, explore other research questions relevant to mHealth intervention scale-up for postnatal South Asian women, and explore generalizability across populations.